The invention relates to new compounds that can be used by themselves or in mixtures in detergent additive compositions for fuels.
It is known that automobile engines have a tendency to form deposits on the surface of the engine elements, in particular on the carburetor orifices, the bodies of butterfly valves, fuel injectors, cylinder orifices and intake valves, because of oxidation and polymerization of various hydrocarbon-containing components of the fuel. These deposits, even when they are present only in small amounts, are often responsible for significant driving problems, such as the engine timing and poor acceleration. In addition, deposits on the engine can significantly increase the consumption of fuel and the production of pollutants. This is why the development of effective detergent additives for regulating these deposits assumes a considerable importance and was already the object of much research.
A new family of compounds that exhibit good effectiveness as additives that are intended to reduce the deposits on the injectors and on the intake valves has now been discovered.
The compounds of the invention can be defined by the following general formula (I): 
in which R1, R2, R3, and R4 each represent a hydrogen atom or a hydrocarbon radical, for example alkyl, with 1 to 30 carbon atoms, whereby at least one of R1, R2, R3 and R4 is a hydrocarbon radical; m and mxe2x80x2 are each a number from 1 to 30, preferably 1 to 20, with m+mxe2x80x2 from 4 to 60, preferably 5 to 30.
In the same formula (I), the concatenations 
can respectively consist of patterns: 
that differ from one another by the nature of R1, R2, R3 and/or R4.
The compounds of the invention generally come in the form of mixtures of compounds that differ from one another by the value of m and/or mxe2x80x2 and/or by the nature of radicals R1, R2, R3 and R4. Rather than compounds, it is then a matter of compositions.
The synthesis of the compounds or compositions defined above can be carried out as described below.
The isosorbide of formula: 
is reacted with one or more compounds that have an epoxide group, with general formula: 
in which R1, R2, R3, and R4 each represent a hydrogen atom or a hydrocarbon radical, for example alkyl with 1 to 30 carbon atoms, whereby at least one of R1, R2, R3 and R4 is a hydrocarbon radical.
The stages of the preparation are generally as follows:
a) In a first step, the isosorbide is transformed into an alkaline metal alcoholate (for example sodium or potassium), by reaction with an alkaline hydroxide (for example soda or potash), an alkaline hydride or any other compound that can form an alcoholate with the isosorbide;
b) in a second step, the alkaline alcoholate triggers the polymerization of the epoxide(s) by opening its (their) rings; and
c) in a third step, the alcoholate-termination polyether that is formed is treated by water, an acid or any other compound with mobile hydrogen, in order to transform the alcoholate terminations into alcohol groups.
Described below, by way of illustration, is a special operating procedure, whereby it is understood that the preparation of the compounds and compositions of the invention can be carried out by any other equivalent method.
The isosorbide is mixed with, for example, sodium hydride (at a rate of, for example, about 0.5% by weight). After having purged, under stirring, the reactor of the released hydrogen, an epoxide or an epoxide mixture is introduced in an amount that is calculated to obtain the desired value of m+mxe2x80x2 at a temperature of 80 to 180xc2x0 C., and the reaction mixture is kept at this temperature until the consumption of the epoxide(s) is finished. After returning to ambient temperature, the medium is diluted with an organic solvent, for example a hydrocarbon solvent, such as heptane, it is washed with water one or more times, then, after evaporation under reduced pressure of the organic phase, the desired product that corresponds to general formula (I): 
is obtained.
The compositions of the invention can be used as detergent additives in the gasoline-type fuels. In this application, they can be added to the fuels at concentrations of, for example, 20 to 5000 mg/liter. They can also be used mixed with any other detergent compound.